Hayward a



UNITED (STATES PATENT OFF-ICE.

HAYWARD A. HARVEY. OF ORANGE, JERSEY.

GUN.

SPECIFICATION forming part of Letters Patent No. 460,261, dated September 29, 1891.

Q Application filed October 21, 1890. Serial No. 368.769; (1T0 model.)

To all whom it may concern:

Be it known that I, HAYWARD A. HARVEY, of Orange, New Jersey, have invented a certain Improvement in Ordnance, of which the following is a specification.

The object of this invention is to produce a steel cannon or other piece of ordnance the barrel or tube of which, While in other respects homogeneous, presents upon its interior a cylindrical stratum of steel which is excessively hard upon its concave surface, but which gradually diminishes in hardness as the depth from the concave surface increases, and is adjoined by a cylindrical stratum of steel of any desired thickness which is of considerable toughness and which is incapable of being hardened so as to be brittle, but which is surrounded by anexterior cylindrical stratum of steel of prescribed thickness excessively hard upon its convex surface and also gradually diminishing in hardness from its exterior surface to the place of its union with the tough and comparatively soft steel of which the inclosed cylindrical stratum is composed.

The objects of this construction are as follows: first, to provide an interior surface for the tube or barrel which is so hard that it is incapable of being cut or scratched by the action upon it of the projectile when the gun is fired; secondly, to provide a cylindrical stratum of steel which possesses tenacity and toughness without the brittleness, which is the unavoidable characteristic of hardened steel; thirdly, to provide upon the vexterior of the barrel a cylindrical stratum of steel which is so hardened 'as to give it the quality of elasticity without excessive brittleness and which acts as an inextensible hoop, which completely surrounds the body of softer steel and efiectively prevents it from being permanently expanded by the force of the explosion when the gun is fired. Q The cylindrical stratum of comparatively soft steel acts as a bufie'r to protect the exterior stratum of hard steel from the immediate shock of the explosion, which, but for the interposition of the stratum of comparatively soft steel, might be sufficieut to burst the exterior stratum of hardened steel. These results are accomplished by treating the barrel or tube of the gun, after the same has been cast or forged sions, byl'filling the gun to the muzzle with finely-powdered charcoal and embedding the barrel of the gun in an external body of finely-powdered charcoal contained in a re ceptacle from which the air is excluded and which is constructed of refractory material, such as fire-brick, and which is contained within a furnacechambeigin which there is maintained aheat suflicient to melt cast iron for a period of such duration as will suffice to cause those portions of the metal which are in contact with the charcoal to absorb prescribed percentages of carbon in addition to the carbon originally contained in the steel from which the gun has been made. This process of treatment is analogous to that d'escribed in Letters Patent of the'United States No. 376,194, issued to Hayward A Harvey January 10, 1888.

The duration of the described treatment will of course. vary according to the sizeof the gun and also according to the efficiency of the furnace and the character of the fuel em-- ployed. The necessary data for determining the effects produced by the use for an observed period of a given fuel in a given furnace. The longer the high heat is mainta ned the greater will be the depth of penetration of the added carbon and the greater .will be the quantity of carbon absorbed by thestrata of metal in contact with charcoal.-

In'view of the multiplicity of furnaces, the variety of fuels,and the various sizes of guns, no general prescription canbe given which will be of universal applicability. For illus tration,it may be stated that a prolongation 10f the heat for a period of thirty. hours, after the furnace-chamber has been brought up to a temperature high enough to melt cast-i ron, will usually be sufficient for the efiective treat ment of guns of, say, four inches caliber. By such treatment a gun composed of steel originally containing, say, one-quarter of one per cent. of carbon will be supercarbonized upon its interior and exterior surfaces to such an extent that the surface strata of metal will each contain from one to one and-one-tenth per cent. of carbon. The next adjoining annular stratawill contain say, nine-tenths per cent, the next seven-tenths per cent, the

the duration are ascertaina-ble by observing next five-tenths per cent, and next threetenths per cent-., until at depths of, say, th reequarters of an inch from the exterior and, say, half an inch from the interior surfaces,

the metal will contain only its original quar-v ter per cent. of carbon. Upon hardening the gun by removing it from the furnace, allow- I ing it to cool down to a dull redcolor or other desired color, and then plunging it into water or other tempering-fluid, the supercarbonized adjoining the surfaces which have been in contact with the charcoal, those surfaces will be so hard that-they cannotbe cut or scratched by an ordinary cold-chisel or file. The next adjoining annular stratum will. be slightly less hard, the next still less hard, and so on. Itwiflof course beunderstood that the expressions stratum and strata are herein used merelyfor convenience, and that in any supercarbonized stratum of given thickness there will be a regularly varying distribution of carbon, the quantity present gradually diminishing from the side nearest the exposed surface toward. the side farthest therefrom. The resultant gradual diminution in the degree of hardness in the metal as the distance-from the exposed surfaces increases is a feature of great importance, for if a stratum of excessive hardness, owing to the presence in it of .a large percentage of' carbon, immediately adjoined a stratum containing so little carbon as to be incapable of being hardened the highly-can.

bonized hard stratum would be liable to be chipped or cracked off by the force of the explosion. This feature ismade use of in the construction of the armor-plate described in H. A;Harveysapplication, Serial No. 364,887, filed September 13,1890. In the present case it is desiredthat thereshall be a comparatively shallow depth of supercarbonization of the metal upon the interior surface of the gun'- barrel, the object being to make the interior surfaceof the gun-barrel capable of taking so hard a temper that it will not be abraded by the contact with it of the projectile when the gun is fired. For the strengthening effect the external supercarbonized stratum is mainly relied upon, and as th'eje'xternalportion of the gun is that which is most nearly exposed to the heat of the furnace-chamber there is no difiiculty in-so regulating the 'duration of the treatment as to effect the desired greater depth of supercarbonizationof such external portion.

What is claimed as the inven tion is.

l. The herein-described gun, composed of a mass of steel which, while otherwise homogeneous, contains variahly-distribnted percentagesof carbon and the barrel of which is com posed of an annular stratum of metal containing a relatively low percentage of carbon.

inclosed between internal andexternal annular strata of metal excessivelyhard upon their exposed surfaces and gradually diminishing in hardness as the depths from their exposed surfaces increase, as and for the purpose setforth.

' 2. A steel gun the barrel of which is composed ofabody of steel homogeneouslyunited to the exterior of an annular stratum of metal containingvariably-distributed percentages of carbon and which is excessively hard upon its exposed concave surface, but gradually diminishes in hardness asthe depth from its exposed concave surface increases, as and for the purpose set forth.

3. A steel'gun, the barrel of which is composed of abody of steel homogeneously united to the interior of an annular stratum of metal containing variably-distributed percentages of carbon and which is excessively hard upon its exposed convex surface, but gradually diminishes in hardness as the depth from its exposed convex surface increases, as and for the purpose set forth,

HAYWARD A. HARVEY. Witnesses:

E. "GA TERER, J. E. BURNS. 

